It is common with gas-operated water heaters to dispose the flue centrally, or sometimes offset from the central axis of the water tank so that the hot gases from the lower burner chamber are cooled as they rise up the flue or chimney which is in contact with the water being heated. In order to enhance this heat exchange between the exhaust flue gas and the water within the tank, baffles have been secured in the exhaust flue. An early patent teaching such method is U.S. Pat. No. 953,958 issued in 1910 wherein a chain and a plurality of discs are suspended within the flue to retard the rising gases so that the side wall of the flue absorbs heat and exchanges it with the liquid disposed thereabout. Since then a great number of baffle structures have been constructed and a popular one is to use a twisted spiral metal strip suspended or otherwise disposed within the flue. Examples of these are numerous and can be seen such as in U.S. Pat. Nos. 4,742,800, 4,953,510 and 1,859,745.
It is also customary with these flues to install dampers in an upper end thereof outside the water heaters whereby to maintain heat retention within the flue to cause the heat therein to further dissipate within the water if the temperature thereof is higher than that of the water. Also, when the flue cools down, a reverse effect occurs wherein the hot water then loses heat through the flue. Thus, the reason for the damper.
A disadvantage of known flue baffles is that they are complex in construction and with many of these it is necessary to weld numerous metal tabs onto a cold rolled steel twisted strip. Various errors do occur in that often not enough tabs are welded on the strip or too may tabs are welded. If there is not enough tabs, it affects the performance of the flue baffle and if there are too many this could cause a very dangerous condition by offering too much resistance. Such baffles, including the ones disclosed in U.S. Pat. Nos. 1,859,745 and 4,953,510 can be costly to produce.